Linalool and methyl chavicol present basil ( Ocimum sp . ) cultivated in Brazil

In Brazil, Ocimum species are commonly known as aromatic and restorative herbs. The present research aimed to study the chemical composition of the essential oils of fresh and dry basil (Ocimum sp) leaves obtained by hydrodistillation and analyzed by GC-FID and GC-MS. The obtained yield was 0.70% for dry leaves and 0.26% for fresh leaves. The major compounds were: linalool (29.50-32.26%) and methyl chavicol (36.81-41.62%). Eucalyptol could also be detected (9.99-7.68%). The oil from dry leaves presented a more complex chemical composition. This study serves to contribute to the knowledge of medicinal plants occurring in Brazil.


INTRODUCTION
The Ocimum genus (Lamiaceae family) includes approximately 60 species, normally found in tropical and subtropical regions (Paton, 1992).Ocimum species have encouraged great economic interest due to their medicinal properties and aromatic chemical characteristics (Amaral et al.,1999;Werker et al.,1993), which allow their use in perfume and cosmetic industries.They are also commonly used as condiments in sausage and frozen food industries, as well as in their natural form (Martins et al., 1994).In Brazil, there are a number of Ocimum species (Gupta, 1994), which are commonly found as aromatic and restorative herbs that alleviate spasms, lower fevers, and improve digestion, in addition to being effective against bacterial infections and in the fight against intestinal parasites (Lorenzi & Matos, 2002).In the state of Bahia, basil (Ocimum sp.) has been used in the treatment of fever and flu symptoms (Moreira et al., 2002).The aim of the present study is to investigate the composition of the essential oil of fresh and dry leaves of Ocimum sp., a medicinal plant commonly used by the Brazilian people and widely marketed throughout Brazil.

Plant material
Aerial parts of Ocimum sp at flowering stage were collected, at random, in August 2009 in Vila Cachoeira, located on Ilhéus-Itabuna highway, Km 13, longitude 39º08'96"W and latitude 14º48'55"S, in Ilhéus, Bahia, Brazil.The voucher specimen was deposited in the Herbarium of Univ Estadual de Santa Cruz (HUESC) under the number HUESC 10.126.The fresh leaves were dried by forced ventilation at 50ºC (De Leo & Cia LTDA) for 3 hours until a constant weight was reached.

Essential oil
The plant material underwent hydrodistillation using a Clevenger apparatus for 2 hours.The oil was separated by using dichloromethane, dried with anhydrous sodium sulfate and concentrated.The essential oil content was determined in triplicate (mL of oil per 100g of plant material).

Chromatography analysis
The essential oils were analyzed by means of a Saturn Varian 3800 gas chromatograph (FIDdetector).This chromotograph was equipped with a VF-5ms capillary column (30m x 0.25mm x 0.25µm film thickness), using helium as a carrier gas, together with a flow rate of 1.0 mL min -1 , and an injection temperature of 250 o C. The column programming began at 100º C per min., followed by a continuous increase of 10ºC until the temperature reached 300ºC, which was maintained for 5 min.The sample was dissolved in MeOH to provide a 10% w/v solution; 1µL of sample solution was injected in the split 1:10.GC-MS qualitative analyses were performed by using a Varian Chromopack 2000 MS/ MS equipped with the same VF-5ms capillary column and the same column programming.The operation mode was an electron impact of 70eV, scan rate, 1 scan/s, mass range 40-650 Da.The trap and the transferline temperature were 200 o C and 250 o C, respectively.The compounds were identified from their linear indices on VF-5ms column, determined based on a homologous series of C 8 -C 26 n-alkanes (Doolh & Kratz, 1963), and by comparing their mass spectral fragmentation patterns with those stored in the data bank (NIST02) and in the literature (Adams, 2007).

RESULTS AND DISCUSSION
The dry leaves offer greater oil yield, 0.70%, compared to that from fresh leaves, 0.26%.In the essential oil from dry leaves, 13 compounds could be identified (Table 1), including 45.49% oxygenated monoterpenes, 0.45% monoterpenes, 9.74% sesquiterpenes, and 37.91% phenylpropanoides.Linalool (29.60%) and methyl chavicol (36.81%) proved to be the major compounds.In the essential oil from the fresh leaves, seven compounds could be identified, including 44.75% monoterpenes, 7.12% sesquiterpenes, and 41.62% phenylpropanoids.Eucalyptol was detected at the largest amount in the oils of dry leaves.The oil from dry leaves presented a greater complexity.Methyl eugenol, E-caryophyllene, bicyclogermacrene, β-guaiene, and tau-cadinol could only be observed in the oil from dry leaves.Linalool (32.26%) and methyl chavicol (41.62%) proved to be the major compounds, similarly to the essential oil from the dry leaves.
The difference in the chemical composition of these oils may be attributed to the process of drying the plant material.The drying process is of utmost importance for these aromatic species (Radunz et al., 2002;Corrêa et al., 2004;Costa et al., 2005), since it sets the metabolism of the plant, immobilizing the harmful enzymatic action of the existing active principles (David et al., 2006).The temperature used in the drying process of this species led to a loss of major compounds, Table 1.The heat used in the drying process was from an  (Klimánková et. al, 2008).The chromatographic profile of essential oils of Ocimum sp cultivated in Bahia shows proximity to the essential oil of O. basilicum species; therefore, the relationship among different forms of O. basilicum can be considered reticulate, whereas the group taxonomy can be considered difficult (Graeyer, et al., 1996).
There are differences in the yield and chemical composition of essential oils obtained from fresh leaves and dry leaves of Ocimum sp, commonly used as medicinal plants by Brazilians.Although the drying process is important for the use of medicinal plants, there is a need for further investigations to establish the best drying conditions for this species.

TABLE 1 .
Composition of the essential oils of Ocimum sp